Method of and system for the dynamic scheduling of requests to access a storage system

Abstract

A method and system in a data processing system for dynamically scheduling the processing of a plurality of requests to access a disk, in which each of the plurality of requests is associated with a location on the disk, processes the requests in a first sequential order and determines the amount of time necessary to process a selected number of requests associated with locations between the current location on the disk and the most urgent request. At a time that is earlier than the deadline for processing the most urgent request by the amount of time necessary to process the selected number of requests, the method commences processing of the selected number of requests in a second sequential order.

Description

1. Technical FieldThe present invention relates to data processing systems, and in particular to a method and system in a data processing system for dynamically scheduling a plurality of requests which include real-time and non-real-time requests.2. Description of the Related Art:Devices in a data processing system, such as disk drive adapters, are usually connected via a bus to transmit data from one device to and from other system resources, such as the central processor and memory. Each of these devices has data that it normally transfers. For example, one device may normally transfer real-time data such as is necessary to display a multimedia presentation. A second device may normally transfer non-real-time data that may be a file transfer. A third device may transfer both real-time and non-real-time data. The data transferred by these devices may be stored in a disk drive.Real-time data is data that has an associated deadline. The deadline defines the time by which the real-tim...

AI Technical Summary

Benefits of technology

It is yet another object of the present invention to provide a method and system in a data processing system for dynamically scheduling the processing of a plurality of requests that processes urgent real-time requests in a timely manner, while minimizing back-and-forth movement of the disk arm.

Problems solved by technology

Failure to transfer real-time data prior to the associated deadline will result in lost data.

Often, however, when both real-time and non-real-time data are supported simultaneously, real-time data is not transferred in a timely manner without adversely affecting non-real-time data transfer.

Thus, as real-time requests become urgent, the arm may tend to "jump around" servicing real-time requests on a most-urgent basis.

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